What I have done is to team up with several well-known freefont designers, and use their fonts as a starting point to make updated professional quality multilingual Unicode fonts - and then offer them at a very low price and with very generous licensing terms.

All the reworking is done under agreement with the original designers, and they receive royalties from the sales.

It is a bit more work making these fonts than first meets the eye - I do not simply make some generic diacritics, slap them together with the existing letters and generate the fonts. That would be sloppy ;)

First I check the outlines of the existing letters, fixing any bad nodes, often normalizing the spacing and adjusting some glyphs. Then I take a close look at the kerning, improving it where necessary and preparing it for OpenType class kerning. Only when the basic font is OK do I start expanding the character set, always using diacritics that matches the design of the letters - usually all diacritics are totally redesigned. Finally I generate and test the fonts, make graphics and text for their presentation and prepare the files for download.